Grant-in-Aid for Overseas Scientific Survey.
|Section||University-to-University Cooperative Research|
|Research Institution||Daido Institute of Technology|
OKUDA Takayoshi Daido Institute of Technology . Faculty of Engineering . Professor, 工学部, 教授 (30022990)
RAVEN M.S. University of Nottingham . Faculty of Engineering . Lecturer, 工学部, 講師
BOWLEY R.M. University of Nottingham . Faculty of Science . Professor, 理学部, 上級講師
MAXWELL K. University of Nottingham . Faculty of Science . Senior Lecturer, 理学部, 講師
KING P.J. University of Nottingham . Faculty of Science . Senior Lecturer, 理学部, 上級講師
関谷 昌久 大同工業大学, 工学部, 助教授 (20075906)
日置 義明 大同工業大学, 工学部, 助教授 (50156551)
岩間 三郎 大同工業大学, 工学部, 教授 (00075904)
柴田 長吉郎 大同工業大学, 工学部, 教授 (90206136)
M.S. Raven ノッチンガム大学, 工学部, 講師
R.M. Bowley ノッチンガム大学, 理学部, 教授
K. Maxwell ノッチンガム大学, 理学部, 上級講師
P.J. King ノッチンガム大学, 理学部, 上級講師
SEKIYA Yoshihisa Dido Institute of Technology . Faculty of Engineering . Assoc. Professor
SHIBATA Chokichiro Daido Institute of Technology . Faculty of Engineering . Professor
IWAMA Saburo Daido Institute of Technology . Faculty of Engineering . Professor
HIOKI Yoshiaki Daido Institute of Technology . Faculty of Engineering . Assoc. Professor
|Project Fiscal Year
1990 – 1992
Completed(Fiscal Year 1992)
|Budget Amount *help
¥5,400,000 (Direct Cost : ¥5,400,000)
Fiscal Year 1992 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1991 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1990 : ¥1,800,000 (Direct Cost : ¥1,800,000)
|Keywords||High temperature superconductors / Kosterlitz-Thouless theory / Electrical dissipation / Epitaxial thin film / Whisker / Fine powder / 高温超伝導 / Kosterlitz-Thouless理論 / 散逸過程 / エピタキシャル薄膜 / ウィスカー / 微粒子 / スパッタリング / 薄膜 / ウイスカ- / 電子ビ-ム蒸発法 / Surfaguide / エッチング / Vortexーantivortex pairing|
The Kosterlitz-Thouless theory for the electrical dissipation in the high temperature superconductors predicts scaling of the current voltage characteristics above th phase transition temperature (Tc) but not below. We give an expression for universal scaling curve which provides an excellent fit to the data for epitaxial YBa_2Cu_3O_7 thin films taken in zero applied magnetic field.
Unusual low magnetic field behaviours have been observed in samples of the YBCO composite sinters which contain an appreciable proportion of the insulating 211 phase. These composite materials exhibit a phase-transition in their electrical characteristics at a temperature Tp which is less than Tc the mean field superconducting transition temperature. As an applied magnetic field is increased from zero at temperatures below Tc, the electrical dissipation exhibits a minimum at about 5 Gauss, before it increases in the manner usually found in the superconducting ceramics. At temperatures below the phase transit
ion temperature Tp, a further sharp minimum in the dissipation develops at zero field.
We have investigated features in the current voltage (I-V) characteristics of YBa_2Cu_3O_7:Y_2BaCuO_5 composite sinters which indicate the occurrence of a second-order phase transition. For each sinter composition similar families of characteristics are found for a wide range of magnetic fields. the relation between V and I is seen to be of the form V=f(I, xi (B,T)) where simple parameter xi contains all of the field and temperature dependence. The locus of points in the B,T plane for which xi (B,T) is a constant have been examined, and a low field and a high field regime have been identified. Samples of different composition show families of I-V characteristics which scale onto one another in a simple way, hence we are let to suppose the V = f(I, xi (B,T,p)) where p is the dilution fraction. Data taken at temperatures below transition, with exponents which are independent of magnetic field and composition. Above the transition, however, the behavior is more complex.
Growth condition of the high temperature superconducting whiskers has been investigated in the BSCCO(2212) system. Growth rate of the whisker depends strongly on Bi content in the melt-quenched glass substance and an annealing temperature.
Superconducting fine powder has been prepared by spray pyrolysis. Hydrogen peroxide which is added in the nitrid acid solvent is found to suppress the impurity formation in the powder. A higher abundance (90%) of Low-Tc phase was achieved. Less